The invention relates to a magnetic head unit comprising a magnetic head secured to a support and having a magnetic head structure provided with a head face and at least one transducing gap terminating in the head face.
The invention also relates to a magnetic head and to a magnetic head structure for use in the magnetic head.
A support in the form of a housing comprising a magnetic head unit is known from U.S. Pat. No. 5,074,486; herewith incorporated by reference. The known magnetic head unit comprises a magnetic head intended for cooperation with a magnetic tape, which head is mounted in a housing provided with tape guides. The magnetic head has a magnetic head structure with a tape contact face and a transducing gap.
In a recording/reproducing system it is important that during recording signals on a magnetic tape, a write gap of a magnetic head is at the same position and at the same angle with respect to the magnetic tape as a read gap during reading the recording signals, in order to inhibit signal loss. Said tape guides of the known magnetic head unit ensure that the magnetic tape always occupies the same position with respect to the magnetic head. For reasons of compatibility it is also required that the transducing gap of the magnetic head occupies a defined position with respect to the tape guides of the housing. To this end, magnetic heads are aligned as to position and direction before they are built in. In the case of thin film heads, use can be made of a visible layer terminating in the head face, for example, a flux guide layer. For bulk heads, the visible transducing gap itself may be used as a reference.
A known drawback of magnetic heads which are in contact with a magnetic medium, particularly a magnetic tape, during operation is that the head face is subject to wear. Particularly in thin-film magnetic heads the thin-film layer structure may give rise to very considerable wear within a short period of operation, thus ensuring only a short lifetime of the magnetic head unit. It is known per se to provide wear-resistant layers on the head faces of magnetic heads in order to inhibit wear. In this connection it has been proposed in EP-A 0,123,826 (herewith incorporated by reference) to provide the head face of a magnetic head with a sputtered layer of titanium carbide, chromium carbide or titanium nitride having a thickness of at most 0.2 micron.
A drawback of providing a wear-resistant layer, particularly a layer which is not transparent to visible light, is that the alignment of the magnetic head with respect to a support or a housing of the magnetic head unit is seriously impeded and is no longer possible with the aid of a visible-light microscope. Under such circumstances, only special equipment using, for example, an IR microscope or a phase-contrast microscope provides the possibility of reliable alignment.